一个日历小程序的实现 - 黑马程序员技术交流社区

package test;
import java.util.*;
import java.text.DateFormatSymbols;
/**
* @author Demomiku E-mail: 448902872@qq.com
* @date 创建时间：2015年5月3日下午8:28:14
* @version 1.0
*/
public class MyCalendar
{
public static void main(String[] args)
{
GregorianCalendar d = new GregorianCalendar();
//获得今天是这几月的第几天，这个月是几月，获得的月份是实际月份-1，因为从0开始
int today = d.get(Calendar.DAY_OF_MONTH);
int month = d.get(Calendar.MONTH);
//设置日期为这个月第一天
d.set(Calendar.DAY_OF_MONTH, 1);
//获取第一天是一个星期的第几天
int weekday = d.get(Calendar.DAY_OF_WEEK);
//获得一个星期的第一天
int firstDayOfWeek = d.getFirstDayOfWeek();
//日历开头空格的计数
int indent = 0;
while (weekday != firstDayOfWeek)
{
indent++;
d.add(Calendar.DAY_OF_MONTH, -1);
weekday = d.get(Calendar.DAY_OF_WEEK);
}
//日历第一行输出星期的缩写
String[] weekdayNames = new DateFormatSymbols().getShortWeekdays();
do
{
System.out.printf("%4s", weekdayNames[weekday]);
d.add(Calendar.DAY_OF_MONTH, 1);
weekday = d.get(Calendar.DAY_OF_WEEK);
}
while (weekday != firstDayOfWeek);
System.out.println();
for (int i = 1; i <= indent; i++)
System.out.print(" ");
d.set(Calendar.DAY_OF_MONTH, 1);
do
{
//打印日期
int day = d.get(Calendar.DAY_OF_MONTH);
System.out.printf("%3d", day);
//在今天的后面加上"*"
if (day == today) System.out.print("*");
else System.out.print(" ");
// 将日期+1
d.add(Calendar.DAY_OF_MONTH, 1);
weekday = d.get(Calendar.DAY_OF_WEEK);
// 如果这天是一个星期的第一天则换行
if (weekday == firstDayOfWeek) System.out.println();
}
while (d.get(Calendar.MONTH) == month);
// 如果判断到是下个月了则结束循环
if (weekday != firstDayOfWeek) System.out.println();
}
}

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